There's noway a drop in filter is going to lean our cars out... Especially 0.5 A/F of a difference, that's a huge increase over stock filters. Now, on a side note, EVOs obviously have turbos so that's going to force a lot more air into the engine through the intake then something that's naturally aspirated.

Drop-in filters are extremely safe. I would know because I ran a wideband when I had my test pipes and catback installed with HKS drop-in filters. My fuel curve didn't change at all. The only time I actually leaned out a little bit was when I added the Stillen G3 cold air intakes.

 

I agree Staples, can't see the HKS filters changing the a/f that much either. The EVO is an entirely different beast compared to our cars, hard to compare FI to NA. Now I can imagine if there was a change in A/F, Cobb would be concerned with that since forced induction has a narrow window of tuning and a leaner condition is never good. Staples - what type of A/F curve did you see when you dynoed before/after tune? If the G is anything like my old Altima, they run pretty pig rich from the factory - very safe tune.

 

So is there a verdict on HKS hybrid filter? Worth getting them? What are some other filters that are better than stock?

 

Seems like a bunch of people are running the HKS and like them. I haven't had any complaints so far, but then again they are just filters. Cosworth also makes an aftermarket drop-in that should be pretty good: Performance Air Filter - Performance Air Filter - Cosworth USA

 

The car actually did run rich with the stock intakes and just drop in filters. It wasn't until I added the G3 intakes that I leaned out a lot. I would see about a 12.2-12.4 a/f under wide open throttle with just the drop ins, test pipes, and catback exhaust. After adding the stillen CAIs I was hitting 13.4 - 13.6 A/F.

After my tune at WOT the car would gradually get down to the 12.7 range at redline which seems to be a pretty potent combination for power when adding ignition timing.

 

thats kind of my thought as well...

 

How about Injen, i thought they have a patented technology to keep stock A/F ratio and considerable gains? (not as high as stillen, but more than others)

 

Injen's design is still within the engine bay where only a certain amount of air gets to them. The positive side, it won't lean the car out too bad, the negative is that they won't make as much power as Stillen's. Either option you choose you can't go wrong, I just didn't to change my window shield wiper fluid reservoir.

 

If you were to install a new filter or sri or cai or whatever and reset the ECU shouldnt the ECU re tune itself to be proficient with the new hardware